There are winter winds from the Andes, but in the summer season there are cold currents of air from up-river (ventos da cima) which are usually followed by downpours of rain.
The rains typically start in July and October brings the heaviest downpours with frequent flooding in the capital.
Eighty thousand properties are at risk in towns and cities from flooding caused by heavy downpours that overwhelm urban sewers and drains.
The day had held mixed weather with bright, warm sunshine being followed by very heavy downpours of rain.
The layout had some big jumps and heavily rutted sections courtesy of rain on Friday and intense downpours Sunday morning.